1. Field of the Invention
This invention relates to mineral containing thermoplastic granules and their production and use especially in the production of thermoplastic end products.
2. Brief Description of the Prior Art
It is well known in the production of thermoplastic materials and articles produced from such materials, eg by mixing or compounding followed by a shaping process such as molding, extrusion or blowing, to incorporate in the material an additive known as a blowing agent which when the material is heated and/or compressed during processing causes release of a gas into the material. Foamed lightweight materials may be produced thereby. In the prior art, the blowing agent is incorporated as a separate ingredient in the composition to be mixed or compounded together with the other ingredients to be included in the composition. Extensive mixing of the blowing agent with the other ingredients and the base thermoplastic, ie the thermoplastic material which will provide the matrix in the end product, is required in the compounding stage to ensure that these ingredients are fully and homogeneously mixed throughout the material to be formed.
It is an object of the present invention to provide an improved, more convenient way of introducing a blowing agent into a thermoplastic material.
It is also an object of the present invention to provide an improved method of nucleating gas release from a blowing agent in a thermoplastic material.
It is also an object of the present invention to provide a new granule form suitable for providing a carrier medium for introducing a blowing agent into a thermoplastic material.
These and other objects which will become apparent are met by the present invention.